High-frequency generator



Patented Nov. 16, 1926. I v UNITED STATES PATENT OFFICE.

CARTERAE M. LAFFOON, OF IRWIN, PENNSYL VANIA, ASSIGNOR TO WESTINGHOUSE ELECTRIC & MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA.

HIGH-FREQUENCY GENERATOR. Application filed June 2a, 1923. Serial No. 647,842.

My invention relates to high frequency A. preferred method of making the inducgenerators and it has particular relation to tor consists in assembling the pole members generators of the inductor type, 11113101381 position'in a jig and casting there- One object of'my invention 15 to provide around a body of non-magnetic, electrically an improved generator of the above characconducting material of high tensile strength, so ter, which is adapted to generate voltages of such as phosphor bronze, to form one in-' desired wave shape andwhichis very eflicient tegral disc-shape body which may be subin the elimination of losses caused by the sequently worked to its final shape indicated pulsating flux induced by the high frequency in the drawing. The method just described ar at re current, provides a mechanically strong construction as A second object of my invention is to prowhich is, in electrical respects, superior to vide an improved alternator in which the the structures used at present, as will be extroubles caused by bearing currents that are plained hereinafter. characteristic of alternators of the inductor In machines having inductors of solid type are eliminated. magnetic material, the polar-projections 00- 70 In carrying out my invention, I provide, operating with the slotted stator cores are instead of the usual inductor consisting of obtained by slotting the circumference of a disc-shaped body of magnetic material the inductor. The slots are thereafter filled having polar projections cooperating with with non-magnetic members in order to obthe stator core, an inductor whose mainbody tain a smooth surface andto decrease the 7 is made of nonmagnetic, electrically conwindage. In some machines the non-magducting material of high tensile strength, a netic tillers are made of electrically conduct- -plurality of members of magnetic material ing material and arranged to give a closed being embedded within such body to proelectr cal circuit around each pole. 2 vide the poles of the inductor. It 18, however, exceedingly difiicult to'ob- 80 My invention will be best understood by tain a mechanically satisfactory construcreference to the accompanying drawing, tion without affecting the shape of the poles.

wherein The latter is of, primary importance in high Figure 1 is a vertical sectional view of a frequency generators, and Fig. 2 shows the a t f an alternator embodying my invenshape of the magnetic pole members 15 as 85 tion, and used in the inductor 12 made according to Fig. 2 is an enlarged sectional view on the my invention, the pole members being lin II-11 of Fig. 1, .illu trating'th tat rounded or beveled at their ends adjacent to slots and the pole members of the inductor. the re 4 nd 5. It would be exceedingly Referring to Fig. 1, an annular stator difficult to provide a construction employing no fr 1 f agneti at rial arri s two poles of the shape just described in rotors of members 2 and 3 of ring shape, to which are sOl.d magnetic material as the SlOtS between secured annular cores 1 and5 of laminated the P lar proj c i ns of the rotor have to magnetic material. Each of the cores 4 and be o shaped as to retain the non-magnetic 5 is secured between a flange 6 and a ring fil rs in place. I Y

7 by means of bolts 8. The laminated cores- Vith the inductor constructed in accordhave opposite faces 9 lying in adjacent raance with my invention, an ideal solution dial planes and provided with radially-disof the above mentioned problems is obtained; posed slots 10 carrying an alternating-cur-- the magnetic-poles may be shaped according rent winding 11. Between the adjacent to the most minute requirements as to the faces of the laminated cores extends 'the wave shape; the rotating surface is smooth outer portion of the inductor, which comand gives low \vindage losses; and the slotted prises a disc-shaped body 12 of non-magconducting body gives a perfect damping netic -material mounted Securely upon a winding aroundthe poles and embodies, at

=' l shaft 13, as by means of nuts 14. The nonthe same time, a mechanically perfect 0011- magnetic inductor 12 has magnetic pole struction. j members 15 of roper shape embedded or In this connection, I will point out the otherwise secured radially therein to co-opimportance of a good damper winding inerate with the teeth 16 between the slots 10 high-frequency alternators of the inductor of the laminated cores 4 and 5. type. The principle of operation of such Y trouble. By the alternators is well known. A flux of constant strength is produced by an exciting winding 17 and traverses the stator cores, entering the magnetic pole members 15 -on one side andleaving the same on the other, as indicated by the arrow 18 in Fi 1. The total flux is constant; it is the pu sation of the fluxes interlinked with the respective winding conductors in the stator slots that produces the high-frequency voltage in said windings. The wave shape of the voltage depends upon the rate of change of the magnetic flux across the gap between the opposite teeth of the stator core, and this is determined by the shape of the magnetic poles in the inductor. Only the parts of the magnetic circuit which carry the windings and which are subjected to the pulsations of the fiuxare of laminated material.

It is of importance to restrict the pulsations of the flux to the laminated portions of the magnet-1c path and to eliminate the material, such as the inductor pole members.

ne source of flux pulsation in the inductor pole members is the efiect of the teeth and slots of the stator. Another source is the reaction of the single-phase currents in the armature conductors in the stator. The pulsations due to the first source are to a certain extent reduced by making the slot openings asnarrow as slots of the overhung type. The pulsations due to the armature reaction cannot be eliminated, except by providing the rotor with a damper winding which encloses the pole members and opposes any change of flux therein. Accordingly, a good damper winding is essential for the reduction of the losses and for good performance of the generator, and it is obvious that the solid body of highly conductive electrical material which surrounds the magnetic pole mem bers in the indicator made according to; my invention, provides a damper winding which is not'equaled by any other construction.

There is a further advantage connected with an alternator embodying my invention. Inductors of solid magnetic material produce an -excessive stray field. The stray field penetrates the bearing and induces, in the rotating shaft, an electromotive force which causes the bearing and the solid frame of the alternator to be traversed by currents which are a source of constant use of an inductor of nonmagnetic material, a considerable reduction of non-magnetic possible, that is by of the stray field is effected and the bearing current is almost entirely abolished.

l/Vhile I have of construction of inductor, my invention covers any other form of inductor embodying the principles outlined above, and I aim, in the appended claims, to cover all changes and modifications within the spirit and scope of my invention.

I claim as my invention:

1. In a high-frequency generator, a rotor material, having insets of magnetic material, the cross-section of which is greater at the interior than near the surface of said rotor, whereby the non-magnetic material holds said insets in place.

2. In a high-frequency generator, a stator havinga body and two circular rows of teeth. the teeth of each row extending from said body towards the teeth of the other row and each tooth being wider at the end farther from the body, thereby providing overhung slots between the teeth, in combination with a rotor of non-magnetic material extending into the space between said rows of teeth, said rotor having pole members of magnetic material each extending radially a distance approximately equal to the radial length of the teeth, extending through the rotor nearly the distance between the rows of teeth,

and extending circumferentially a greater distance in the interior of the rotor than adjacent its surfaces.

In a high-frequency generator, a stator having a body and two circular rows of teeth, the teeth of each row extending from saidbody towards the teeth of thefiother row arid each tooth being wider at the end farther from the body, thereby providing overhung slots between the teet in combiof non-magnetic materows of teeth, said rotor havin rs of magnetic material eac radially "a distance approximately equal .to the radial length extending through the rotor nearly the distance between the rows of teeth, and extending circumferentially a greater distance in the interior of the rotor than adjacent its surfaces, the edge surfaces of said ole piecesbeing rounded whereby a desira 1e wave form is given to the output of the generator.

In testimony'whereof, I have hereunto subgcribed my name this 22nd day of June, 192

pole mem- OARTHRAE M. LAFFOON.

the space between said,

indicated a preferred form 

